Rectifier



May 29, 1928.

' A. MAVROGENIS RECTIFIER Filed July 18, 1923 I Patented May 29, 1928,

UNITED STATES PATENT OFFICE.

anrs'ro'rn navnoenms, or mnwauxnn, wrsconsm.

RECTIFIER.

Application an m 18,

10 tubes for transmitting or receiving wireless messages, the'filainent of such tubes, the electromagnets of loud speakers, or other devices which require a supply of electric energy of constant intensity. These rectiw fiers asheretofore constructed have not been suitable for direct connection to alternating current lighting mains for supplying -electric energy of unvarying intensity. Further,

these devices, if'of the thermionic type have quire a large internal voltage drop, and have been bulky and cumbersome.

This invention is designed to overcome the above noted defects and has for its primary object the provision of a constant current rectifier which is adaptedito be directly con- 1 ected to an alternating current supply system and to furnish direct'currentof uniform and non-fluctuating value.

Further objects are to provide: a rectifier adapted to furnish'electrical energy of unvarying value which is certain in its functioning, which. has a low internal voltage drop, which is eflicient, which has an increased life, which is heated by alternating current, and which is compact.

Further objects are to provide an uipotential cathode, to provide for the heating of such cathode by radiation, conduction, or both, as by means of a filament or resistance heater.

Further objects are to rovide means for constant and for keeping it at equal potential throughout its entire active surface although it is heated by alternating current, and to provide a devlce in which substantiallyl all the ener y supplied for heatingthe cat ode is useful yemployed and losses are reduced to aminimum. I Further objects are to provide as a unitary device, a rectifier and a thermionic apparatus for holding the rectified current at Ya constant value, in which the same or difl'erent heaters may be used forthe rectifier and been of relatively short life, ineflicient, re

1923. Serial N0. 652,266.

filter or current limiting device, and to provide a system emplo ing this unitary device in such a manner that constant current of any desired value may be obtained.

- Embodiments of the invention are shown in the accompanying drawings, in which Figure 1 is a set of curves illustrating the voltage and current values in rectifying devices.

Figure 2 is a set of curves illustrating the relation between plate current and the plate voltage of certain thermionic devices.

Figure 3 is a diagrammatic view of one form of the apparatus having certain connections inside the tube.

Figure 4.- is a diagrammatic view of one form of. theapparatus in which the cathodes of the rectifier and current filter are heated by independent auxiliar cathodes or heaters.

Figure 5 is a view showing the cathodes heated by a common heater.

F igure 6 is a view illustrating the mechamcal construction of one form of device such as illustrated in the diagrammatic views.

Figure 1 shows a set of curves plotted with time as the abscissas illustrating the action of a rectifier, and will first be described. In

the figure the curve A shows an alternating current, and in dotted lines the unused portion when one half of each of the waves is rectified. Curve B shows the value of the rectified current, which may be smoothed out sponding voltage curve is shown at D, for

this partially smoothed out current with the maximum and minimum voltages indicated by E and E and the variation voltage or difference indicated by E I It is highly desirable in certain kinds of work, particularly radio work, to obtain a practically constant current from alternate ing current supply mains, and in this work even minute fluctuations'must be avoided. I, therefore, propose to combine with arectifier, such as a thermionic rectifier, a current filter or limiter, of the thermionic type. This current filter or limiter I combine with the rectifier as ,a single unitary device, and I have found that when desirable the same or different means may be employed for heating the cathodes of both devices. I therefore combine with the rectransformer. The secondary 4 of t e transtifier a thermionic current filter .to which I apply the pulsating unidirectional voltage from the rectifier in a manner to saturate the thermionic current filter at the minimum voltage supplied thereto.

Figure .2 shows at Y the characteristic curve for a thermionic device in which the plate voltage is plotted as the abscissas and the plate current as the ordinates. The

dotted line W showsthe curve for an ideal thermlonic device: The curve X shows the Figure 4 shows one way'of practicing the invention..'- The alternating current mains 1 and 2 are connected to the primar 3 of a former supplies the plate current fora compound thermionic device. This device consists of an evacuated vessel 5 which may-be either partially or wholly divided into two compartments by) a sultable partition 6.

Two filaments ,7 and 8 are connected with "thlS tube" is illustrated m Figure 6-, which will be'described in detail hereinafter.

Figure 5 shows a form of the device in the mains 1 and 2 through suitable independent rheostats 9 and 10. The device is equip d with cathodes 11 and 12 which are heate byradiation from the filamentsfi'and 8' respectively to al uniform temperature. They are referably composed of tungsten, nickel, mo ybdenum, or similar metal, and are preferably coated on the side towards the filamentswvith a nickelous oxide. On the side, towards the plates they are preferably coated with an oxide having a low electron aflinit such as barium, strontium, thorium, or ca cium oxide to increase their electron emission. -Plates 13 and 14 are arranged in close proximity, to the cathodes audaccurately parallel them.

The upper device indicated generally R in the form shown, is the rectifier and its anode or plate 13 is connectedto one'side of the secondary; Its cathode 11 is connected 1 shown and indicated generally'at F. v Theby means of the conductor 15 with the anode of the current filter or thermionic limiting device which is the lower device in the form cathode 12' of the filter is connected tothe positive out ut terminal 16. The other out put termina 17 is'connected to one side of the secondary*4 of the transformer by-means of the conductor 18. If desired, a condenser 19 may .be bridged across the conductors 15 and 18 to partially smooth out the pulsafions from the rectifier before reaching the this form of the appa- I maintained at a constant, non-fluctuating temperature, and the electron emissive power of the cathodes does not vary. Obviously,

the actual current flowing through the rec-. tifier varies, that is to say, comes in pulses, but the current through the filter is pf aaj. steady and unvarying value. Consequently so a the current supplied the work circuit (not shown) varying.

,Figure 3 shows a construction similar to that shown in Figure 4, with the exception that the filaments are connected in series by means of the conductor 38 inside of the vessel, and that the cathode 1-1 of the rectifier, is connected to the anode 14 of the current limiting device by meansof-the conductor 45, located inside the vessel. The

from the terminals 16 and 17 is unsame numbers have been used as in Figure 4, as far as possible, with the exception that suflixes are added to certain of the reference characters. The mechanical construction of which the rectifier R is provided with two plates 20 and 21 connected to opposite terminals of the secondary 22 of the trans-.

The cathode 24 is con-' nected by means of the conductor 25 with v the anode; 26 of the current filter F. A condenser 27 is bridged across the conductors 25 and 28 and partially smooths out the fluctuations before they reach the current limiting device or filter F; The cathode 29 is'connected to the positive delivery terminal 16 and if desired a condenser 30 may be bridged across the terminals 16 and 17.

the choke coil 23 and condenser 30, 'anduthedouble anode of the rectifier. One or the other of these anodes 20 and 21 is passing current to the cathode 24 for each pulse of the alternating current. In this manner a more nearly constant suppl of energy is furnished by the rectifierbe ore it is finally smoothed out by the current filter.

Figure 6 shows the mechanical construc- I tion of. the apparatus illustrated diagram- Lenses matically in Figure 3 in'which Separate filamentary heaters are provided for each of the main cathodes of the current filter and current rectifier and are connected in series figure so that comparison of the illustrations may be most readily made.

The evacuated vessel 5 may take the form of the usual bulb, such as employed in vacuum tube work and may be provided with a cylindrical base 33 equipped with a plurality of prongs 34 electrically connected to the different portions of the device.

The partition 6 may or may not extend completely across the apparatus. form shown in Figure 6 it extends only part ly across and does not hermetically seal on,

separately the two portions of the device. The partition is carried in a recess formed in the porcelain or other similar type of main support 35 which is suitably carried by a glass or other type of pillar 36 from the lower portion of the apparatus. This porcelain support 35 is provided with aset of helical grooves which carry the filament 8 of the filter and the filament 7 of the rectifier. One terminal of the filament 8 is connected to the end of the conductor 37 and its other end' is connected to one end of the filament 7.- The upper end of the filament is connected by meansof a conductor 38 which extends upwardly out of the porcelain main support 35 and joins the downwardly extending conductor 39 which passes centrally through such main support 35 and through the pillar 36. This figure, it will be seen, difiers slightly from Figure 4 in the arrangement of filaments, that is to say, while the filaments have been shown in parallel in Figure 4 they are shown in series in this figure. Obviously though, either arrangement could easily be made in a simple and readily appreciated manner. The main support 35 is provided with flanges 40 at its upper and lower ends and with a centralfiange which is provided with a slot and receives the partition 6. Upon these flanges, the cathode 12'? of the filter and 11 of the rectifier rest. This main support and the associated electrodes may be of any desired shape and in the form shown is roughly oval shape. The plate 13 of the rectifier is spaced from the cathode 11 thereof and is carried by relatively rigid con-.

/ ducting supports 41 which are carried by the upper end of the insulating support 42 through whichthe conductor 43 is passed.-

This conductor is electircally connected to the stiff wires 41 and to one of the prongs.

The plate 14 of the filter is spaced from the cathode 12 thereof and is carried by means of relatively stifi supports 44, one of In the heated by which may be connected by means of conductor 45 with the cathode 11 'of the rectifier .andwith one of the prongs. This last conductor may extend downwardly from the metal supports 46 of the plate 13 and through the insulating glass pillar. It corresponds to the conductor 15 in Figure 4.

It is to be notedthat accurate parallelism of the plates and cathodes in the two portions of the device may be most readily attained and that the spacing of such portions.

may be extremely small'if desired thus correspondingly varying and improving the electrical characteristics of the device. It is further to be noted that all of the energy from the filaments is transmitted to their cathodes either by radiation or conduction, and that even the-lightwhich is radiated from the filaments, when luminous filaments are employed, is transformed into heat in the cathodes and is prevented from escaping from the device. This obviously, improves the electrical efficiency of the apparatus.

Obviously, various other mechanical embodiments of the invention may be employed but it is thought that the selection described will illustrate in a clear way the different modes which may be followed in a physical embodiment of. the device. It is intended that the current filter shall be a high vacuum apparatus in all forms of-the invention.

It is to be noted that the relatively heavy porcelain or other type of sup ort for the filaments acts in themanner o a fly wheel so to speak in that it stores up a material .in maintaining a uniform temperature for the cathodes.

It is to be noted that in each of the several forms of the device that the cathode of the filter is an etiuip otential surface and is an auxi alternating current. It is also to be noted that the temperature, of the main cathode v of the filter remains constant and does not follow the fluctuations due to the alternating current. It is to be further noted that this type of cathode ma be also employed in a number of the recti ers which are combined with the filter.

If it is found desirable the coiled filament may have its halves or different portions, wound in opposite directions to avoid any transformer action from such filament.

It is to be further noted that-by employing the plate type, either flat or curved, of anode and cathode that exact parallelism of the parts may be assured. --This is particularly desirable in the current filter or current limiting device.

iary means energized from It will further be s eenthataeconstantcur.-

rent rectifier has-been provided which-is adapted; r; energization from. alternating current an which will supply a constant d1- tio'nal constant value current from altern'atie'g .cdr' e t, mpr sing-M. a ed f 2. A. unitary. combined insaid vessel, a= f .ypon each of. saidi g embers, a cathode. sur-. rounding each Qifllid' mei'nbe s and heated 'rect current oinongfluctuating yalue,

Although certain embodiments of the-in: I zvention have been, described with consider- .able detail, it isto be-understoodthat. the

e-P i tgsuppa infi m mbe at i fitting filament wound by thejcorrespondin-g filament, and an anode surrounding each-= of said cathodes and spaced therefrom, said members beingbod-" ily separate and distinct.

' rectifier and current limitingr levice for'supplying unidirectional constant value cu1 rent.from alternatng current comprismgan evacuated vessel,

a pair of supporting members located with in said. vesse l, i a heatingsfilamentiwound t erefrom, said members bei rate and distinct, anda shiel ing pate in p anode, heating means for said cathodes "upon'each of said members, a cathode sur-' rounding eachof said -members and .heated by' the-corresponding filament, an anode su rroundin'g each of said cathodesand spaced bodil sepa terpbsed between, said members.

31A unitary" electron .dischar'ge' devioe.

comprising an evacuated; vessel enclosing a pa r'of insulating members having marginal flanges, a heating filament wound upon each memberbetween the flanges, acathode car ried by eachmember and supported upon the flanges of the corresponding. members, a

- 'shieldi1i "platelocated between the mem- -bers,.an :an anode surrounding each cathode; ijfi -gkieunitary electron discharge, device; com rising an evacuated vessel enclosing a'n'j insu ating member, a. pair of heating filam n sa we d F01 said mber aw d. relation, acatho de positionedjadjacent each filamentf nd h l y said zm'ember in spaced relationg-to the corresponding filament,- and an anode surrounding each cathode.

5;: A unitary electron discharge 7 device comprising an. evacuated vessel enclosing an insul ating... member having two portions mounted in axial alignment with a groove formed between them,each portion having mi ang a a e g ament o n tweeathe end flanges .of eac of said portrons, a sheet metal cathode surrounding each ,pprtion andcar'ried at opposite-ends by. the

flan e a rad a s-1a h el P t cated within'thesaid groove and projecti outwardly from said member, and anano dfi 'surroundmg ieach cathode. Y

' 6, A unitary rectifier.and currentfimiting deviceflfor supplying constant value unidirectionahcurrent. from alternating i current, said device comp'rising'an evacuated. vessel an anode,'. a cathode positioned adjacent said anode, jasecond anode, means for-"connecting'said secondanode with said' cathode, a second cathode 'positionedadjaceht said secondanode,- ,and lleating means 'for'-' said .second cathode adapted for I energization al-. .ternating current, I i 1 77; A unitary rectifier and current limiting" device] 'comprisingJan evacuated vessel, an

anode, a cathode, positionedadjacentsaid anode, 1 second anode, means "for'connecting said fseiond anode with said cathode, a second cathode positioned adjacent said seeond adapted;-for energization by alternating cur v.rent, an in'putQterminaI connected to. the

wardly't-hrough' the'walls of said vesse e Intestim'ony that I claim the foregoing haVe-hereuntoset my hand at Milwaukee, in the county "of Milwaukee State-of Wisims'mcremvno ems- 

